Racquet configured with increased flexibility in multiple directions with respect to a longitudinal axis

ABSTRACT

A racquet includes a frame extending along a longitudinal axis. The frame includes head and handle portions, and a throat portion positioned between the head and handle portions. The head and throat portions are formed at least in part of a fiber composite material. The material includes a plurality of ply arrangements. Each of the arrangements includes one ply having a first plurality of fibers defining a first angle with respect to a composite axis, and another ply having a second plurality of fibers defining a second angle with respect to the composite axis. The first and second angles are substantially the same except the angles have opposite polarities with respect to the composite axis. The head portion includes at least three arrangements overlaying each other, and the first and second angles of at least two of the at least three arrangements are at least 35 degrees.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119 fromco-pending U.S. Provisional Patent Application Ser. No. 62/641,600 filedon Mar. 12, 2018 by Severa et al. and entitled RACQUET CONFIGURED WITHINCREASED FLEXIBILITY IN MULTIPLE DIRECTIONS WITH RESPECT TO ALONGITUDINAL AXIS, the full disclosure of which is hereby incorporatedby reference.

FIELD OF THE INVENTION

The present invention relates generally to a sports racquet. Inparticular, the present invention relates to racquet configured withreduced resistance to bending about a longitudinal axis of the racquetin at least a first direction that is parallel to a string bed of theracquet and a second direction that is perpendicular to the string bedof the racquet, while maintaining torsional stability.

BACKGROUND OF THE INVENTION

Sport racquets, such as tennis racquets, are well known and typicallyinclude a frame having a head portion coupled to a handle portion by athroat portion. The head portion supports a string bed having aplurality of main string segments alternately interwoven with aplurality of cross string segments.

Players generally continually seek more control, more power and/or abetter feel from their racquets. Highly skilled tennis players typicallyseek to impart spin onto the tennis ball when impacting the ball. Theability to impart a spin (a top spin or a back spin) to a ball increasesa player's ability to control the ball and to hit the ball with morepower during play. For example, imparting a top spin onto a tennis ballcan enable a player to swing faster, hit the tennis ball harder andstill keep the tennis ball in play within the court. Imparting a topspin to a ball can enable a player to aim higher, swing faster, clearthe net and keep the ball in play. Skilled tennis players also seek aracquet that provides the sense or feel of an increased “dwell time” orcontact time between the racquet and the ball upon impact. The increaseddwell time improves not only the responsiveness of a racquet, but alsoits control, including the ability to impart spin on the ball. The swingused by highly skilled tennis players to impart a top spin on to atennis ball includes an upward sweeping motion in combination with theforward swinging motion. Such a top spin swing is more difficult toperform well than a more horizontal swing because the upward and forwardmotion of the head portion of the racquet during a top spin swingresults in a shorter time window for impacting the ball. The upwardsweeping motion of a racquet swing used to impart a top spin onto a ballalso produces more of a lateral load onto the racquet during impact.

Racquets are continually designed in an effort to improve performanceand playability of the racquet. Many existing racquets include highracquet frame beam heights and other racquet geometries that increasethe racquet stiffness in an effort to improve the performance of theracquet. Other existing racquets incorporate a larger sized hoop portionsupporting a larger sized string bed (i.e., a larger head size) in aneffort to increase the size of the string bed and the racquet'sperformance. However, as the head size of a racquet increases, so doesthe polar moment of inertia of the racquet. A racquet with a higherpolar moment of inertia can be more difficult to maneuver, particularlyat the net or upon return of serve, than a racquet with a lower momentof inertia. Other existing racquets include designs that seek tolengthen the main and cross string segments comprising the string bed inan effort to increase the performance of the racquet. However, therecontinues to be a need for a racquet that further improves theperformance and playability of the racquet.

There is a continuing need to provide a racquet that offers improvedperformance such as increased control, increased power, and/or improvedfeel. There is an ongoing need to provide an improved racquet designthat seeks to improve all forms of racquet swing motions, including theupward sweeping motion of a topspin swing. There is a continuing needfor a racquet having a string bed with an enlarged sweet spot andproviding an increased “dwell time,” without negatively effecting theoverall performance of the racquet. It would be advantageous to providea racquet with an enlarged sweet spot and an increased “dwell time”without increasing the polar moment of inertia of the racquet head andwithout negatively affecting the maneuverability of the racquet. Thereis also a need for a racquet having a string bed with an enlarged sweetspot that is not a radical departure in look and design from traditionalsport racquet designs.

SUMMARY OF THE INVENTION

The present invention provides a tennis racquet extending along alongitudinal axis and capable of being tested under a lateral bendingtest and a forward/rearward bending test. The lateral bending testincludes mounting the racquet in a first orientation to a first testfixture at a first longitudinal location, attaching a clamp to theracquet at a second location, operably engaging a deflection indicatorto the clamp, applying a first predetermined weight to the racquet at athird location, and removing the first weight to obtain a lateraldeflection measurement of the racquet with respect to the longitudinalaxis. The forward/rearward bending test includes mounting the racquet ina second orientation to the first test fixture at the first longitudinallocation, applying a second predetermined weight to the racquet at afourth location, operably engaging the deflection indicator to theracquet at a fifth location, and removing the second weight to obtain aforward/rearward deflection measurement with respect to the longitudinalaxis. The racquet is rotated 90 degrees about the longitudinal axis fromthe first orientation to the second orientation. The racquet comprises aframe including a head portion, a handle portion, and a throat portionpositioned between the head portion and the handle portion. The headportion forms a hoop that defines a string bed plane. At least the headportion and the throat portion of the racquet is formed at least in partof a fiber composite material. The throat portion includes a pair ofthroat elements. When the racquet is tested under the lateral bendingtest, the racquet has a lateral deflection of at least 6.0 mm whenmeasured in a direction that is parallel to the string bed plane andperpendicular to the longitudinal axis.

According to a principal aspect of a preferred form of the invention,when the racquet is tested under the forward/rearward bending test, theracquet has a forward/rearward deflection with respect to thelongitudinal axis of at least 9.0 mm when measured in a direction thatis perpendicular to the string bed plane and perpendicular to thelongitudinal axis.

According to a principal aspect of a preferred form of the invention, atennis racquet extending along a longitudinal axis and capable of beingtested under a forward/rearward bending test and a torsional stabilitytest. The forward/rearward bending test includes mounting the racquet ina first orientation to a first test fixture at a first longitudinallocation, operably engaging a deflection indicator to the racquet at asecond location, applying a first predetermined weight to the racquet ata third location, and removing the first predetermined weight to obtaina forward/rearward deflection measurement with respect to thelongitudinal axis. The torsional stability test includes mounting theracquet to second and third test fixtures at fourth and fifth locationsof the racquet, respectively, placing a second predetermined weight onan arm extending from the second test fixture to place a torsional loadon to the racquet, removing the second predetermined weight to obtain anangular deflection about the longitudinal axis. The racquet comprises aframe including a head portion, a handle portion, and a throat portionpositioned between the head portion and the handle portion. The headportion forms a hoop that defines a string bed plane. At least the headportion and the throat portion of the racquet is formed at least in partof a fiber composite material. The throat portion includes a pair ofthroat elements. When the racquet is tested under the forward/rearwardbending test, the racquet has a forward/rearward deflection with respectto the longitudinal axis of at least 9.0 mm when measured in a directionthat is perpendicular to the string bed plane and perpendicular to thelongitudinal axis. When the racquet is tested under the torsionalstability test, the racquet has an angular deflection of less than 5.5degrees about the longitudinal axis.

According to another principal aspect of a preferred form of theinvention, a tennis racquet includes a frame extending along alongitudinal axis and including a head portion, a handle portion, and athroat portion positioned between the head portion and the handleportion. The head portion forms a hoop that defines a string bed plane.The throat portion includes a pair of throat elements. At least the headportion and the throat portion of the racquet are formed at least inpart of a fiber composite material. The fiber composite materialincludes a plurality of ply arrangements. Each of the ply arrangementsincludes a pair of plies with one ply having a first plurality of fibersdefining a first angle with respect to a composite axis and the otherply having a second plurality of fibers defining a second angle withrespect to the composite axis. The first and second angles aresubstantially the same except the first and second angles have oppositeangular polarities with respect to the composite axis. The head portionincludes at least three ply arrangements overlaying each other, and thefirst and second angles of at least two of the at least three plyarrangements are at least 35 degrees.

According to another principal aspect of a preferred form of theinvention, a sports racquet is capable of being tested under a racquetvibration test. The racquet vibration test utilizes a modal analysissystem including a hammer, an accelerometer removably attached to theracquet, and a modal analysis frame for supporting the racquet duringmodal analysis in a free-free condition. The racquet comprises a racquetframe extending along a longitudinal axis and including a head portion,a handle portion, and a throat portion positioned between the headportion and the handle portion. The head portion forms a hoop thatdefines a string bed plane. The throat portion includes a pair of throatelements. At least the head portion and the throat portion of theracquet are formed at least in part of a fiber composite material. Thehead portion includes a forward hoop surface and a rearward hoopsurface. The distance between the forward and rearward hoop surfaces isa beam height distance. The head portion has a maximum beam heightdistance of at least 19 mm. When the racquet is tested under the racquetvibration test, the racquet has a vibration of no greater than 130 Hz.

This invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings described herein below, and wherein like reference numeralsrefer to like parts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a racquet in accordance with oneimplementation of the present invention.

FIG. 2 is a front side perspective view of the racquet of FIG. 1 shownwithout a grip and without a butt cap.

FIG. 3 is a side view of the racquet of FIG. 1.

FIG. 4A is a top, side view illustrating a portion of a pair of plies offiber composite material prior to wrapping around a bladder and amandrel in accordance with a preferred implementation of the presentinvention.

FIG. 4B is a top, side view illustrating a portion of a layer of braidedfiber composite material prior to wrapping around a bladder and amandrel in accordance with a preferred implementation of the presentinvention.

FIG. 5 is a side view of a portion of a lay-up or arrangement of layersof fiber composite material prior to molding about a bladder and amandrel.

FIG. 6 is top side perspective view of the lay-up of layers of fibercomposite material of FIG. 5 with the mandrel and the bladder.

FIG. 7 is top side perspective view of the lay-up of layers of fibercomposite material of FIG. 6 with the mandrel removed and the lay-up oflayers curved to approximate the shape of a racquet, and a yoke fibercomposite lay-up.

FIG. 8 is a top side perspective view of the lay-up of layers of fibercomposite material of FIG. 7 prior to being placed into a racquetforming mold.

FIG. 9 is a top side exploded view of the lay-up of layers of fibermaterial being placed into a racquet forming mold.

FIG. 10 is a side perspective view of a racquet lateral bending testassembly and an unstrung racquet undergoing a racquet lateral bendingtest with a first weight applied to the racquet.

FIG. 11 is a top, side perspective view of a clamp removably attached toa distal region of a head portion of the racquet and a deflection meterengaging the clamp under the racquet lateral bending test assembly ofFIG. 10.

FIG. 12 is a side perspective view of the racquet lateral bending testassembly of FIG. 10 with the first weight removed from the racquet.

FIG. 13 is a side perspective view of a racquet forward/rearward bendingtest assembly and a racquet undergoing a racquet forward/rearwardbending test with a second weight applied to a distal region of a headportion of the racquet.

FIG. 14 is a top, side perspective view of a deflection meter and asecond weight applied to the racquet under the racquet forward/rearwardbending test assembly of FIG. 13.

FIG. 15 is a side view of the racquet forward/rearward bending test ofFIG. 13 with the second weight removed from the racquet.

FIG. 16 is a top, side perspective view of a racquet torsional stabilitytest assembly and a racquet undergoing a racquet torsional stabilitytest with a third weight applied to the racquet torsional stabilityassembly.

FIG. 17 is a first end, side perspective view of the racquet torsionalstability test assembly of FIG. 16.

FIG. 18 is a top, side perspective view of the racquet torsionalstability test assembly and the racquet undergoing a racquet torsionalstability test of FIG. 16 with the third weight removed from the racquettorsional stability assembly.

FIG. 19 is a top, end perspective view of a vibration analysis testbeing performed on a racquet.

DETAILED DESCRIPTION OF THE PREFERRED IMPLEMENTATIONS

Referring to FIGS. 1 through 3, a sports racquet is indicated generallyat 10. The racquet 10 of FIG. 1 is configured as a tennis racquet. Theracquet 10 includes a frame 12 extending along a longitudinal axis 16and including a head portion 18, a handle portion 20, and a throatportion 22 coupling the head and handle portions 18 and 20. The frame 12is a tubular structure formed of a lightweight, durable material,preferably a fiber composite material.

The head portion 18 is a tubular structure that includes inner and outerperipheral walls 24 and 26. The head portion 18 can be broken down intoregions, such as, a distal region 28, first and second side regions 30and 32, and a proximal region 34, which collectively define a hoop 36having a string bed area 38 for receiving and supporting the string bed14. In one preferred implementation, the proximal region 34 includes ayoke 40. The string bed area 38 is also referred to as the head size ofthe racquet 10. In a preferred implementation, the head size or stringbed area 38 of the racquet 10 is within the range of 93 to 120 squareinches. In other implementations, the head size of the racquet 10 can bewithin the range 98 to 115 square inches. In other implementations,other head sizes can also be used and are contemplated under the presentinvention. The string bed area 38 has a maximum longitudinal dimension,a, and a maximum transverse dimension, b. The hoop 36 can be any closedcurved shape including, for example, a generally oval shape, a generallytear-drop shape, a generally circular, a generally pear shape, andcombinations thereof. In some implementations, the maximum longitudinaldimension a can be at least 1.2 times the maximum transverse dimension b(a≥1.2*b). In other implementations, the maximum longitudinal dimensiona can be at least 1.25 times the maximum transverse dimension b (a≥1.25*b). In other implementations, the maximum longitudinal dimension acan be less than 1.2 times the maximum transverse dimension b.

The yoke 40 is an elongate tubular structural member that extends fromthe first side region 30 to the second side region 32 of the headportion 18. In one implementation, the yoke 40 is integrally formed withthe frame 12 defining the proximal region 34. For example, the yoke canbe formed of a fiber composite material and molded and cured with theframe 12 of the racquet 10. In alternative preferred implementations,the yoke 40 can be connected through use of adhesives, fasteners,bonding and combinations thereof. The yoke 40 is formed of alightweight, durable material, such as a carbon-fiber compositematerial. Alternatively, the yoke 40 can be formed of other materials,such as, for example, other composite materials, metallic alloys, apolymeric material, wood and combinations thereof.

In a preferred implementation, the first and second side regions 30 and32 downwardly extend from the head portion 18 to form first and secondthroat tubes 42 and 44 of the throat portion 22. The first and secondthroat tubes 42 and 44 converge and further downwardly extend to formthe handle portion 20. Accordingly, in such implementations, the frame12 can be formed of one continuous tube of material (e.g., fibercomposite material) that is curved at its middle region to form the headportion 18 then each side of the continuous tube of material canconverge toward each other in the throat region 22 and the end regionsof the continuous tube can be arranged side by side to form the basestructure of the handle portion 20. In such implementations, the frame12 is formed as a one piece integral structure. The handle portion 20can further include a pallet 46, a grip 48 and a butt cap 50. In otherimplementations, the handle portion 20 can be a tubular structure thatdoes not include an extension of the first and second throat tubes. Insuch implementations, the handle portion can be a tubular structureseparate from either the throat portion or the head portion of the frameand attached to the throat portion through use of conventionalfasteners, molding techniques, bonding techniques, adhesives orcombinations thereof. In other implementations, the handle portion canbe formed in the shape of an outer surface of a conventional pallet,thereby eliminating the need for the use of a pallet.

In other implementations, the head portion 18 can be directly connectedto one or both of the throat portion 22 and the yoke 40 through the useof conventional fasteners, adhesives, mechanical bonding, thermalbonding, or other combinations thereof. In one implementation, the headportion 18 can be separated from one or both of the throat portion andthe yoke by a vibration and shock absorbing material, such as anelastomer.

The racquet 10 is configured for supporting a string bed 14 and isformed by a plurality of main string segments 52 alternately interwovenor interlaced with a plurality of cross string segments 54. The stringbed 14 is preferably generally uniform with constant spacing between thestring segments 52 and 54. Alternatively, the string bed 14 can havesome spacing variability provided that the spacing of the main and crossstring segments of the string bed is most dense at the center of thestring bed 14 (or near the geometric center of the string bed or stringbed area). The main and cross string segments 52 and 54 can be formedfrom one continuous piece of racquet string, or from two or more piecesof racquet string. The racquet string is formed of a high tensilestrength, flexible material. In preferred implementations, the racquetstring can be formed of a polyester material, a nylon, a natural gutmaterial and/or a synthetic gut material. The racquet string can beformed in a monofilament construction or in a multiple-filamentconstruction, and can be formed of various different diameters (orgauges). Preferably, the diameter of the racquet string is within therange 1.10 to 1.55 mm.

The inner and outer peripheral walls 24 and 26 of the hoop 36 caninclude string holes 59 for receiving the racquet string. The stringholes 59 can be sized to be just larger than the diameter of the racquetstring, or the combination of the racquet string and a grommet, or asize that is larger to accommodate movement or deflection of the racquetstring and/or grommet. The head portion 18 of the racquet 10 can alsoinclude one or more grommets or bumper guards for supporting andprotecting the racquet string as it extends from one string hole toanother. Additionally, the number of string holes 59 can be varied toproduce different string arrangements or numbers of main string segments52 and cross string segments 54 resulting in different string patterns.Referring to FIG. 3, the inner and outer peripheral walls 24 and 26 ofthe head portion 18 can define a maximum beam height distance d measuredfrom a forward hoop surface 25 to a rearward hoop surface 27. In oneimplementation, the maximum beam height distance d is at least 19 mm. Inother implementations, the maximum beam height distance d can be atleast 20 mm. In other implementations, the maximum beam height distanced can be at least 21 mm. In still other implementations, the maximumbeam height distance d can be at least 22 mm.

Referring to FIGS. 1 through 3, the main and cross string segments 52and 54 refer to the portions of the racquet string that make up thestring bed 14. The string bed 14 extends about and generally defines astring bed plane 56 (or a first plane). The string bed plane (or firstplane) 56 extends through the longitudinal axis 16. A second plane 58,perpendicular to the sting bed plane (or the first plane) 56, alsoextends through the longitudinal axis 16. The sting bed plane 56 existson a racquet whether it is strung or unstrung.

Conventional tennis racquets are typically formed of fiber compositematerial and/or aluminum, and are typically formed to be stiffstructures that resist deflection about the longitudinal axis of theracquet. A stiff racquet construction is generally considered to bedesirable because it is believed to improve the power and/or control ofthe racquet. Conventionally, the stiffness of a racquet generally refersto the racquet's resistance to bending along the longitudinal axis ofthe racquet and with respect to the string bed plane in aforward/rearward direction with respect to the string bed. Racquetstiffness is typically measured in a forward/rearward bending test (or aracquet stiffness test) wherein the handle portion of the racquet isfixedly secured in a test fixture with the string bed (and the stringbed plane) positioned generally horizontal to the ground, a load isapplied to the distal region of the head portion in a direction that isperpendicular to the string bed plane. The load causes the racquet tobend, flex or deflect with respect to the longitudinal axis and thestring bed plane. The amount of deflection is measured to ascertain thestiffness level of a racquet.

High quality racquets are also typically designed to provide high levelsof torsional stability. A torsionally stable racquet resists rotationalmovement of the head portion of the racquet upon an off-center impactwith a tennis ball which improves the control of the racquet.Accordingly, conventional racquet design seeks to produce racquets withhigh levels of racquet stiffness and torsional stability at apredetermined racquet weight or weight range.

The shape and geometry of the head portion 18 and the throat portion 22of the frame 12 of the racquet 10 also contributes to the racquetsstiffness level and/or torsional stability. For example, racquets withhigh racquet beam heights are generally stiffer than racquets with lowerracquet beam heights. The shape and geometry of the throat tubes 42 and44 can also affect the stiffness of the racquet.

Contrary to conventional racquet design, the co-inventors of the presentinvention have identified and developed racquet constructions withdecreased racquet stiffness with respect to the longitudinal axis andthe string bed plane of a racquet and decreased lateral racquetstiffness with respect to the longitudinal axis and a second plane(perpendicular to the string bed plane), while maintaining desiredlevels of torsional stability. Contrary to conventional racquet designand expected results, the co-inventors of the present invention havediscovered that racquets produced with increased longitudinal deflectionalong the longitudinal axis of a racquet with respect to the string bedplane and with respect to the second plane perpendicular to the stringbed plane produce a significantly improved feel with improved controland/or increased power. For example, implementations of the presentinvention with increased flexibility with respect to the longitudinalaxis 16 and the string bed plane 56 and/or the second plane 58, canimprove the dwell time, control and performance of the racquet. In otherimplementations, with increased flexibility with respect to thelongitudinal axis 16 and the second plane 58, the racquets 10 can flexin response to a lateral load, such as the lateral load that is appliedto the racquet upon execution of a top spin swing. The racquets of thepresent invention provide a significantly better feel, and a sensationof increased interaction with the ball particularly during topspinswings which can result in better control and increased power for theplayer.

The co-inventors of the present invention have developed improved fibercomposite racquet constructions that enable the racquet to be producedwith increased levels of deflection (lower stiffness) with respect tothe longitudinal axis while maintaining high levels of torsionalstability.

In one implementation of the present invention, the shape and geometryof the throat tubes 42 and 44 contribute to the flexibility of theracquet 10 with respect to the string bed plane 56 and the second plane58, while contributing to the torsional stability of the racquet 10. Inanother implementation of the present invention, the lay-up of the fibercomposite material used to form the head portion 18 and the throatportion 22 contributes to the enhanced flexibility of the racquet 10with respect to the string bed plane 56 and the second plane 58 whilemaintaining a high level of torsional stability.

As used herein, the term “fiber composite material” or “compositematerial” refers to a plurality of fibers within and permeatedthroughout a resin. The fibers can be co-axially aligned in sheets,layers or plies, or braided or weaved in sheets or layers, and/orchopped and randomly dispersed in one or more layers. A single plytypically includes hundreds or thousands of fiber bundles that areinitially arranged to extend coaxially and parallel with each otherthrough the resin that is initially uncured. Each of the fiber bundlesincludes a plurality of fibers. The fibers are formed of a high tensilestrength material such as carbon. Alternatively, the fibers can beformed of other materials such as, for example, glass, graphite, boron,basalt, carrot, Kevlar®, Spectra®,poly-para-phenylene-2,6-benzobisoxazole (PBO), hemp, flax, other naturalfibers and combinations thereof. In one set of preferredimplementations, the resin is preferably a thermosetting resin such asan epoxy or a polyester resin. In other sets of preferredimplementations, the resin can be a thermoplastic resin. The compositematerial is typically wrapped about a mandrel and/or a comparablestructure, and cured under heat and/or pressure. While curing, the resinis configured to flow and fully disperse and extend throughout thematrix of fibers. In multiple layer or ply constructions, the fibers canbe aligned in different directions with respect to the longitudinal axis16, and/or in braids or weaves from layer to layer.

Referring to FIG. 4A, a portion of a layer 60 of fiber compositematerial is illustrated. The layer 60 is formed by one or two plies 62(62 a and 62 b) of fiber composite material. A ply 62 of fiber compositematerial refers to an arrangement of fibers 64 and fiber bundles 66 in aresin 68, wherein the fibers 64 and the fiber bundles 66 are arrangedand aligned such that the fibers 64 and the fiber bundles 66 generallyextend coaxially with respect to each other and are generally parallelto one another. The fibers 64 or fiber bundles 66 are preferably formedsuch that they extend along the ply 62 and form generally the same anglewith respect to an axis, such as a composite axis 70. The plies 62 aretypically identified, at least in part, by the size and polarity of theangle defined by the fibers 64 or fiber bundles 66 with respect to theaxis 70. As shown in FIG. 4A, the ply 62 a has fibers 64 and fiberbundles 66 aligned at a positive 45 degree angle ply, and the ply 62 bhas fibers 64 and fiber bundles 66 aligned at a negative 45 degree angleply. In other implementations, the plies 62 can include fibers 64 orfiber bundles 66 defining a positive 30 degree angle ply, a negative 30degree angle ply, a positive 45 degree angle ply, a negative 45 degreeangle ply, a positive 40 degree angle ply, a negative 40 degree angleply, a positive 35 degree angle ply, a negative 35 degree angle ply, a90 degree angle ply (extending perpendicular to the axis), and a 0degree angle ply (or extending parallel to the axis). Other positive ornegative angles for plies can also be used. Accordingly, in the presentapplication, a single ply 62 refers to a single layer of fiber compositematerial in which the fiber bundles 66 extend in substantially the samedirection with respect to a longitudinal axis along the single layer,such as plus or positive 45 degrees or minus or negative 30 degrees. Alayer 60 formed of a pair of plies 62 having fibers 64 of generally thesame angle but arranged with opposite polarities is also referred to aply arrangement. This pattern typically extends throughout a fibercomposite material. The alternating angular arrangement of the fiberbundles 66 and fibers 64 is important to achieving and maintaining thestructural integrity of the component or structure being formed of thefiber composite material. The overlapped region of the two plies 62 aand 62 b can be essential for ensuring that, once cured, the fibercomposite material has the desired strength, durability, toughnessand/or reliability.

Conventional fiber composite racquets are formed of fiber compositelayers including plies having angular pluralities of 30 degrees or less,with the exception of a small percentage of layers having a 90 degreeply. The use of layers having plies of angular values of 30 degrees orless are used because layups including such arrangements of layers canprovide the desired high levels of stiffness and also result in lessmanufacturing waste when preparing or cutting plies from large uncutsheets of fiber composite material. Conventional racquet design teachesaway from plies having angular polarities of greater than 30 degreesbecause such higher angled plies would negatively affect the stiffnessof the racquet and would result in unnecessary material waste that wouldunnecessarily increase the manufacturing cost of the racquet.

During heating/molding and curing, the resin 54 can flow between plies62 and within the fiber bundles 66. The plies 62 preferably typicallyhave a thickness within the range of 0.002 to 0.018 inch. In otherimplementations, other thickness ranges can also be used.

Referring to FIG. 4B, in other implementations, one or more of thelayers 60 can include a plurality of braided fibers 62 c. The braidedfibers 62 c can extend at angles with respect to the lay-up axis 70 ofat least 35 degrees with positive and negative polarities. In otherimplementations, the braided fibers 62 c can extend at angles withrespect to the lay-up axis 70 of at least 40 degrees (with positive andnegative polarities).

Referring to FIG. 5, an example arrangement of layers 60 to be wrappedor formed about a mandrel 74 is illustrated. The example arrangement ofFIG. 5 is provided to demonstrate a general process of laying up aracquet frame under an example implementation of the present inventiononly and it is not considered to be comprehensive in any manner. Otherarrangements of layers 60 including other numbers of layers, otherlengths of layers, other widths of layers, other shapes of layers, otherfiber angle values of layers, other sequences of layers, andcombinations thereof are contemplated under the present invention. Thenumber of plies 62 used to form a frame 12 can be within the range of 2to 150. In a preferred implementation, the number of plies 62 used toform the frame 12, or the head portion 18 and throat portion 22 thereof,is at least 10 plies. In other implementations, other numbers of pliescan be used.

The mandrel 74 is a body that is generally shaped to form the internalsurface of the molded component and serves as a core upon which thelayers 60 of fiber composite material can be wrapped or applied over. Inone implementation, the mandrel 74 is an elongate body having agenerally rectangular cross-sectional area with rounded corners. Inother implementations, the mandrel can have other cross-sectionalshapes. A bladder 76 is placed over, and fits around the outer surfaceof, the mandrel 74. Each layer 60 is wrapped or formed about a bladder76 and mandrel 74 and follows the form or shape of the bladder 76 andmandrel 74. In the example arrangement of FIG. 5, 11 layers (layers 60 athrough 60 k) are illustrated with layer 60 a being wrapped firstfollowed by layer 60 b and so on. Importantly, a majority of the layers60 have an angular orientation of 45 degrees (layers 60 a, 60 b, 60 d,60 e, 60 h and 60 k). Each of the layers (60 a, 60 b, 60 d through 60 f,and 60 h through 60 k) include a pair of plies having the same angularvalue but with opposite polarities (e.g. 60 a includes one ply havingfibers extending at a positive 45 degree angle and another ply havingfibers extending at a negative 45 degree angle). Further, the layerswith the 45 degree angular orientation (layers 60 a, 60 b, 60 d, 60 e,60 h and 60 k) form the longer layers 60 of the total number of layersin the lay-up (or plurality of ply arrangements). Accordingly, thehigher angled layers generally extend along the entire length of thelay-up and therefore, when molded and cured, the higher angled layersextend over the head portion, the throat portion and the handle portion.

In other implementations, other numbers of layers 60, lengths of layers60 and angular orientations of layers 60 can be used. In implementationsof the present invention, a plurality of the layers 60 (or plyarrangements) include high angle plies, meaning plies having anglesgreater than or equal to 35 degrees with respect to the composite axis70. In one implementation, at least two layers (or ply arrangements) ina lay-up 80 (see FIG. 6) of fiber composite material of at least fourlayers can each include at least two plies 62 having fibers extending atan angle of at least 35 degrees with respect to the composite axis 70 (a35 degree layer or ply arrangement). In another implementation, at leasttwo layers (or ply arrangements) in the lay-up 80 of fiber compositematerial of at least four layers 60 can each include at least two plies62 having fibers extending at an angle of at least 40 degrees withrespect to the composite axis 70 (a 40 degree layer or ply arrangement).In another implementation, at least two layers (or ply arrangements) 60in a lay-up 80 of at least four layers can each include at least twoplies 62 having fibers extending at an angle of at least 45 degrees withrespect to the composite axis 70 (a 45 degree layer or ply arrangement).In other implementations, a lay-up 80 of fiber composite material (orplurality of ply arrangements) of at least four layers 60 can include atleast three layers 60 being at least 35 degree layers. In anotherimplementation, a lay-up 80 of at least four layers 60 can include atleast three layers 60 being at least 40 degree layers. In anotherimplementation, a lay-up of fiber composite material (or plurality ofply arrangements) of at least four layers 60 can include at least threelayers 60 being at least 45 degree layers.

In other implementations, the lay-up 80, or plurality of plyarrangements, can include at least five layers 60, at least six layers60, at least seven layers 60 and higher. In such lay-ups, the number oflayers 60 being at least 35 degree angles can be at least three layers,or four layers, or five layers or more layers. In other implementations,the lay-up 80 or plurality of ply arrangements can include at least fivelayers 60, at least six layers 60, at least seven layers 60 and higher,and the number of layers 60 being at least 40 degree angles can be atleast three layers, or four layers, or five layers or more layers. Instill other implementations, the lay-up 80 or plurality of plyarrangements can include at least five layers 60, at least six layers60, at least seven layers 60 and higher, and the number of layers 60being at least 45 degree angles can be at least three layers, or fourlayers, or five layers or more layers.

In preferred implementations, the length of the high angle layers (atleast 35 degree angle layers, at least 40 degree angle layers, or atleast 45 degree angle layers) extend over at least 40 percent of thetotal length of the lay-up the head portion 18 of the racquet 10. Inother implementations, the length of the high angle layers extend overat least 50 percent of the total length of the lay-up the head portion18 of the racquet 10. In other implementations, the length of the highangle layers extend over at least 70 percent of the total length of thelay-up the head portion 18 of the racquet 10. In preferredimplementations, the length of the layers 60 or ply arrangements can besufficiently long such that, when molded and cured, the high anglelayers (at least 35 degree angle layers, at least 40 degree anglelayers, or at least 45 degree angle layers) extend over at least thehead portion 18 of the racquet 10. In other implementations, the lengthof the layers 60 or ply arrangements can be sufficiently long such that,when molded and cured, the high angle layers (at least 35 degree anglelayers, at least 40 degree angle layers, or at least 45 degree anglelayers) extend over at least the head portion 18 and the throat portion22 of the racquet 10.

In one implementation, at least 50 percent of the layers 60 of a lay-upor plurality of ply arrangements can be formed with carbon fibers. Inanother implementation, at least 75 percent of the layers 60 in a lay-upor ply arrangement can be formed of carbon fibers. In oneimplementation, each of the high angle layers (at least 35 degree anglelayers, at least 40 degree angle layers, or at least 45 degree anglelayers) in the lay-up 80 include a resin and have a fiber area weight ofat least 100 g/m². In another implementation, each of the high anglelayers (at least 35 degree angle layers, at least 40 degree anglelayers, at least 45 degree angle layers, or at least 60 degrees) in thelay-up 80 include a resin and have a fiber area weight of at least 120g/m².

Referring to FIG. 6, when the layers 60 are wrapped or laid up aroundthe bladder 76 and the mandrel 74, the plies 62 are no longer arrangedin a flat sheet, and therefore, the fiber bundles 66 and fibers 64 nolonger follow or define generally parallel lines. Rather, the fiberbundles 66 and fibers 64 are adjacent to one another, and are curved orotherwise formed so that they follow substantially the same adjacentpaths. For example, when the ply 62 is wrapped about the bladder 76 andthe mandrel 74, the ply 62 can take a generally cylindrical or tubularshape and the fiber bundles 66 and fibers 64 can follow the samecylindrical path or define a helical path (depending upon their anglewithin the ply 62). The fibers 64 remain adjacent to one another, arealigned with each other and follow substantially similar paths that areessentially parallel (or even co-axial) for example, when viewed in asectional view in a single plane or other small finite segment of theply 62.

In one implementation, the mandrel 74 may include a pull tab 82 forfacilitating the pulling or removal of the mandrel 74 from the pluralityof layers 60 wrapped about the bladder 76 and the mandrel 74. The lay-up80 of FIG. 6 is uncured. In one implementation, the mandrel 74 using thepull tab 82 can be drawn, pulled or otherwise removed from the bladderand the lay-up 80.

Referring to FIGS. 7 and 8, once the mandrel 74 is removed from thebladder 76 and the lay-up 80, the uncured lay-up 80 can be gentlypositioned into the shape of a racquet frame. An uncured yoke lay-up 84of fiber composite material can be prepared for positioning next to thecurved lay-up 80. As shown in FIG. 8, the lay-up can be shaped toresemble a racquet frame, and the yoke lay-up 84 can be attached to thelay-up 80. In one implementation, additional relatively short ties ortying plies can be applied over the connection points of the yoke lay-up84 to the lay-up 80. In other implementations, the yoke lay-up may bereplaced with a preformed yoke structure that is added attached to thelay-up 80 prior to molding.

Referring to FIG. 9, the uncured lay-up 80 and the uncured yoke lay-up84 is positioned within a mold cavity 88 of a racquet forming mold 90. Asupply line 86 can be attached to the bladder 76 for supplying air orother gas to the bladder, and the pieces of the racquet forming mold 90can be positioned around the lay-up 80 and the yoke lay-up 84. Thebladder 76 can be pressurized by air or other gas to a predeterminedpressure, and the racquet forming mold 90 can then be heated in an ovenor furnace to a predetermined temperature. Once subjected to heat andpressure, the viscosity of the resin 68 in the lay-up 80 and the yokelay-up 84 drops and the resin 68 flows through out the plies 62 of thelay-up 80 and yoke lay-up 84 in the mold cavity 88 creating a moreuniform structure and the fibers 64 are positioned into the shape of themold cavity. After a first predetermined amount of time, the racquetforming mold 90 is removed from the heat and the lay-up 80 and yokelay-up 84 are allowed to cool. After a second pre-determined amount oftime, the racquet forming mold 90 is opened and the racquet frame 12 isremoved from the mold 90. The frame 12 of the racquet 10 can have aweight within the range of 260 gm to 355 gm. In other implementations,the frame of the racquet can have a weight outside of the 180 gm to 370gm range.

The incorporation of high angle layers 60 (at least 35 degree anglelayers, at least 40 degree angle layers, at least 45 degree anglelayers, or at least 60 degree angle layers) into the lay-up 80 of theframe 12 of the tennis racquet 10 provides unique combination ofperformance characteristics that unexpectedly and significantly improvethe feel and playability of the racquet. The incorporation of high anglelayers 60 into the lay-up 80 of the frame 12 of the tennis racquet 10can result in the racquet 10 having a high amount of deflection in aforward/rearward racquet stiffness test, a high amount of deflection ina lateral racquet stiffness test, while maintaining a high level oftorsional stability under a racquet torsional stability test.Accordingly, racquets built in accordance with implementations of thepresent invention can exhibit low or reduced longitudinal stiffness withrespect the longitudinal axis 14, the string bed plane 56 and the secondplane 58, while maintaining a desirable amount of torsional stability.This combination of attributes is unique to racquet construction andresults in racquets having exceptional feel, playability, control and/orpower.

Racquets built in accordance with the present invention can provide anumber of significant advantages to users of the racquets.Characteristics such as, (1) racquet deflection measured with respect tothe longitudinal axis of the racquet in a forward/rearward directionwith respect to the string bed plane 56, and (2) racquet deflectionmeasured with respect to the longitudinal axis of the racquet in alateral direction with respect the second plane 58 can be substantiallyincreased through use of racquets built in accordance with the presentinvention. Additionally, racquets built in accordance with the presentinvention exhibit desirable levels of torsional stability, andexceptionally low frequency values which improve the feel of theracquet. Further, racquets built in accordance with the presentinvention exhibit relatively low vibration levels contributing toimproved feel of such racquets.

Racquets built in accordance with the present invention, when tested ina racquet lateral bending test, can provide a lateral deflection of atleast 6.0 mm when measured in a direction that is parallel to the stringbed plane and perpendicular to the longitudinal axis. Accordingly,racquets built in accordance with the present invention have a reducedresistance to bending with respect to the longitudinal axis in adirection parallel to the string bed plane and perpendicular to thelongitudinal axis. In other implementations, a racquet built inaccordance with the present invention, when tested in a racquet lateralbending test, can provide a lateral deflection of at least 6.5 mm whenmeasured in a direction that is parallel to the string bed plane andperpendicular to the longitudinal axis. Additionally, in otherimplementations, a racquet built in accordance with the presentinvention, when tested in a racquet lateral bending test, can provide alateral deflection of at least 7.0 mm when measured in a direction thatis parallel to the string bed plane and perpendicular to thelongitudinal axis.

Racquets built in accordance with the present invention, when tested ina racquet forward/rearward bending test, can provide a forward/rearwarddeflection of at least 9.0 mm when measured in a direction that isperpendicular to the string bed plane and perpendicular to thelongitudinal axis. Accordingly, racquets built in accordance with thepresent invention have a reduced resistance to bending with respect tothe longitudinal axis in a direction perpendicular to the string bedplane and perpendicular to the longitudinal axis. In otherimplementations, a racquet built in accordance with the presentinvention, when tested in a racquet forward/rearward bending test, canprovide a forward/rearward deflection of at least 10.0 mm when measuredin a direction that is perpendicular to the string bed plane andperpendicular to the longitudinal axis. In other implementations, aracquet built in accordance with the present invention, when tested in aracquet forward/rearward bending test, can provide a forward/rearwarddeflection of at least 10.5 mm when measured in a direction that isperpendicular to the string bed plane and perpendicular to thelongitudinal axis. Additionally, in other implementations, a racquetbuilt in accordance with the present invention, when tested in a racquetforward/rearward bending test, can provide a forward/rearward deflectionof at least 11.0 mm when measured in a direction that is perpendicularto the string bed plane and perpendicular to the longitudinal axis.

Racquets built in accordance with the present invention, when tested ina racquet torsional stability test, can also provide an angulardeflection of less than 5.5 degrees. In other implementations, a racquetbuilt in accordance with the present invention, when tested in a racquettorsional stability test, can provide an angular deflection of no morethan 5.0 degrees.

Still further, racquets built in accordance with the present inventioncan provide frequency values from modal analysis of no greater than 135Hz. In other implementations, racquets built in accordance with thepresent invention can provide frequency values from modal analysis of nogreater than 130 Hz. In other implementations, racquets built inaccordance with the present invention can provide frequency values frommodal analysis of no greater than 120 Hz. In still otherimplementations, racquets built in accordance with the present inventioncan provide frequency values from modal analysis of no greater than 115Hz.

Referring to FIGS. 10 through 12, Wilson Sporting Goods Co. conducted aracquet lateral bending test using a racquet deflection test assembly100. The racquet lateral bending test measures the lateral flexibilityof a racquet, or a racquet's resistance to bending with respect to thelongitudinal axis 16 of the racquet and the second plane 58. The term“racquet lateral bending test” means a test meeting the followingdescription. The string bed, the grip and the butt cap are removed fromthe handle portion of the racquet. Under the racquet lateral bendingtest, the handle portion of the racquet is securely mounted to a firsttest fixture 102 at a first location 104 in a first orientation, inwhich the longitudinal axis 16 of the racquet 10 is parallel to theground and the string plane 56 of the racquet 10 is perpendicular to theground. In one implementation, the first test fixture 102 can be apneumatic clamp. In other implementations other forms of test fixturescan be used. Referring to FIGS. 10 and 11, a test clamp 106 isreleasably, fixedly secured to the racquet 10 at a second location 108,which is at the distal end region 28 of the head portion 18 of theracquet 10 at a 12 o'clock position of the hoop 36. The test clamp 106is a light weight clamp having a weight of less than 50 grams, andincludes a horizontally positioned side surface 110 for operablyengaging a sensing probe 112 of a digital deflection indicator 114, suchas a Digimatic™ Indicator Model ID-150ME by Mitutoyo of Aurora, Ill. Thelocation where the sensing probe 112 of the digital deflection indicator114 engages the side surface 110 is positioned 40 mm from a distal endsurface (at the 12 o'clock position) of the distal end region 28 of thehead portion 18. A first weight 116 is applied to a third location 118of the racquet 10. The third location 118 is positioned on the secondside region 32 of the head portion 18 generally at the 3 o'clockposition of the hoop 36 at a distance that is 20 inches from a proximalend of the racquet 10 along the longitudinal axis 16 of the racquet 10.The first weight 116 is a 3 kg weight, which, when applied to theracquet at the third location 118, causes the racquet 10 to deflect withrespect to the longitudinal axis 16. The sensing probe 112 is positionedto engage the side surface 110 of the clamp 106, and the digitaldeflection indicator 114 is zeroed. Referring to FIG. 12, the firstweight 116 is removed from the racquet 10 and a lateral deflectionmeasurement is taken from the digital defection indicator 114. Althoughthe racquet shown in FIGS. 10-12 is unstrung and although the racquetlateral bending test can also be performed on a strung racquet, forpurposes of the claimed invention, the racquet tested under the racquetlateral bending test is unstrung.

Referring to FIGS. 13 through 15, Wilson Sporting Goods Co. conducted aracquet forward/rearward bending test (also referred to as a racquetstiffness test or a racquet stiffness index test) using a racquetforward/rearward bending test assembly 130. The racquet forward/rearwardbending test measures the flexibility of a racquet in a forward/rearwarddirection with respect to the sting bed plane 56, or a racquet'sresistance to bending with respect to the longitudinal axis 16 of theracquet and the string bed plane 56. The term “racquet forward/rearwardbending test” means a test meeting the following description. The stringbed, the grip and the butt cap are removed from the handle portion ofthe racquet 10. Referring to FIGS. 13 and 14, under the racquetforward/rearward bending test, the handle portion 20 of the racquet 10is securely mounted to the first test fixture 102 at the first location104 in a second orientation, in which the longitudinal axis 16 of theracquet 10 is parallel to the ground and the string bed plane 56 of theracquet 10 is also parallel to the ground. In other words, the racquet10 is rotated 90 degrees about the longitudinal axis 16 from the firstorientation to the second orientation. A second weight 122 is applied toa fourth location 124 of the racquet 10. The fourth location 124 beingthe distal end region 28 of the head portion 18 of the racquet 10 atapproximately a 12 o'clock position of the hoop 36. The sensing probe112 of the digital deflection indicator 114, such as a Digimatic™Indicator Model ID-150ME by Mitutoyo of Aurora, Ill. at a fifth location126, which is at the top side of the distal end region 28 of the headportion 18 of the racquet 10 at the 12 o'clock position. The secondweight 122 is a 2.8 kg weight, which, when applied to the racquet at thefourth location 124, causes the racquet 10 to deflect with respect tothe longitudinal axis 16 and the string bed plane 54. The sensing probe112 is positioned to engage top side of the distal end region 28 of thehead portion 18 at a fifth location 126, and the digital deflectionindicator 114 is zeroed. Referring to FIG. 15, the second weight 122 isremoved from the racquet 10 and a racquet deflection measurement istaken from the digital defection indicator 114. The term“forward/rearward” is meant to refer to deflection of the racquet ineither direction that is perpendicular from the original string bedplane 56 and the longitudinal axis 16 of the racquet. In theforward/rearward racquet bending test, the application of the secondweight to the distal end of the head portion of the racquet causes theracquet to deflect downward in a rearward direction. Then, when thesecond weight is removed, the racquet moves upward in a forwarddirection. The total amount of the forward movement is the deflectionmeasurement (or the stiffness value of the racquet). Although theracquet shown in FIGS. 13-15 is unstrung and although the racquetforward/rearward bending test can also be performed on a strung racquet,for purposes of the claimed invention, the racquet tested under theracquet forward/rearward bending test is unstrung.

Referring to FIGS. 16 through 18, Wilson Sporting Goods Co. alsoconducted a racquet torsional stability test using a racquet torsionalstability test assembly 140. The racquet torsional stability testincludes a frame 142 with second and third test fixtures 144 and 146 formounting the racquet 10 to at sixth and seventh locations 148 and 150 ofthe racquet 10, respectively. The term “racquet torsional stabilitytest” means a test meeting the following description. The string bed,the grip and the butt cap are removed from the handle portion 20 of theracquet 10. The racquet 10 is positioned in the second and third testfixtures 144 and 146 with the longitudinal axis 16 and string bed plane54 of the racquet 10 parallel to the ground. The second test fixture 144fixedly secures the handle portion 20, and is pivotally mounted to theframe 142 to allow for pivotal or rotational movement of the secondfixture 144 (and the handle portion 20 clamped to the second fixture144) about the longitudinal axis 16 of the racquet 10. The second testfixture 144 further includes an arm 152 that radially projects orextends from the second test fixture 144 and the longitudinally axis 16.The arm 152 includes one or more indexes 154 for receiving a thirdweight 156 at a predetermined distance from the longitudinal axis 16. Inone implementation, the third weight is a 6.9 kg weight and thepredetermined distance is 40 cm from the longitudinal axis 16. The thirdtest fixture 146 fixedly secures the head portion 18 of the racquet 10in a fixed position with the string bed plane 56 of the racquet 10positioned parallel to the ground. A digital inclinometer 160, such as aWixey™ Digital Angle Gauge, Model No. WR300, Type 2, by Barry WixeyDevelopment of Sanibel, Fla., is removably mounted to the second testfixture 144 at the longitudinal axis 16. The third weight 156 is appliedto the arm 152 at the predetermined distance of 40 cm from the axis 16.The third weight 156 applied to the arm 152 places a torsional load ontothe handle portion 20 of the racquet 10 and causes rotation of thesecond test fixture 144 (and the handle portion 20) with respect to theframe 142 and about the longitudinal axis 16. Referring to FIG. 18, thedigital inclinometer 160 is zeroed, and the third weight 156 is removed.The angular deflection or movement of the arm 152 and the handle portion20 with respect to the longitudinal axis 16 is measured. Although theracquet shown in FIGS. 16-18 is unstrung and although the racquettorsional stability test can also be performed on a strung racquet, forpurposes of the claimed invention, the racquet tested under the racquettorsional stability test is unstrung.

The advantages of the present invention were illustrated by performanceof the racquet lateral bending test, the racquet forward/rearwardbending test and the racquet torsional stability test on racquets madein accordance with implementations of the present invention and onseveral existing racquet models. Table 1 below lists the results of theracquet lateral bending test, the racquet forward/rearward bending testand the racquet torsional stability test on a total of twenty tworacquets, 3 of the racquets being prototypes of the present invention,and 19 existing, prior art racquet models. All of the racquets weretested unstrung.

TABLE 1 normal lateral bending mm bending mm torsion degrees FlexPrototype 2 12.1 Flex Prototype 1 10.5 Wilson Profile 2.0 Flex Prototype1 12.1 Flex Prototype 2 7.7 Wilson Profile 2.8 Flex Prototype 3 11.2Flex Prototype 3 7.0 Comp Prince Tour 100 7.7 Prince Tour 100 5.7 WilsonUltra 2 3.1 Wilson 7.7 Wilson PS 5.5 SI 5.6 Wilson Hammer 3.1 AggressorHead Radical Tour 5.4 6.2 Head Prestige 7.5 Head Prestige Pro 5.2 WilsonGalaxy 3.4 Pro Head Radical mp 5.0 Wilson Ultra 2 3.5 Head Radical 7.4Wilson Blade 98 4.7 mp Tour Babolat Aero 4.5 Wilson Ultra 85 3.6 WilsonSting 6.5 Wilson Hammer 4.2 Babolat Pure 3.8 Wilson Ultra 2 6.5 6.2Drive Head Radical 6.5 Wilson Galaxy 3.8 Flex Prototype 3 3.9 mp PrinceGraphite 3.7 Wilson PS 5.5 SI 4.3 Prince Graphite 6.4 mp Head Radical4.8 mp Wilson Profile 3.7 Tour Wilson Blade 98 6.2 Comp Babolat Aero 4.8Wilson PS 5.5 5.9 Wilson Ultra 2 mp 3.6 Flex Prototype 1 4.9 SI WilsonUltra 2 3.6 Flex Prototype 2 4.9 Babolat Aero 5.5 Wilson Ultra 85 3.5Wilson Sting 4.9 Wilson Ultra 100 5.3 Babolat Pure Drive 3.5 WilsonBlade 98 4.9 Babolat Pure 5.2 Wilson Sting 3.3 Head Radical mp 5.2 DriveWilson Ultra 100 3.2 Head Prestige 5.4 Wilson Ultra 85 5.1 WilsonAggressor 3.1 Pro Wilson Hammer 5.1 Wilson Profile 3.1 Wilson 5.5 6.2Aggressor Wilson Galaxy 4.7 Prince Graphite 5.8 Wilson Profile 4.1 mpComp Prince Tour 100 6.2 Wilson Ultra 2 3.9 Wilson Ultra 100 6.2 mpWilson Profile 3

The existing, prior art racquets include several older racquet modelsand several current racquet models, all of which are formed at least inpart of fiber composite material. The older racquet models testedincluded the following racquets: Wilson® Profile®; Wilson® Profile®Comp™, Wilson® Ultra® 2; Wilson® Ultra® 2 MP; Wilson® Ultra® 85; Wilson®Ultra® 100; Wilson® Galaxy™; Wilson® Hammer® 6.2; Wilson® ProStaff® 5.5SI; Wilson® Sting™; Wilson® Aggressor® and Prince® Graphite MP. TheWilson® branded racquet models were produced from Wilson Sporting GoodsCo. of Chicago, Ill. from the years 1980 to 2018. The Prince® GraphiteMP racquet was produced in 1983 by ABG-Prince OPCO, LLC of New York,N.Y. The current prior art racquet models tested included the followingracquets: Wilson® Blade® 98; Babolat® Pure Drive™; Babolat® Aero™; Head®Radical® Tour™; Head® Radical® MP and Prince® Tour™ 100. The Babolat®branded racquets were produced by Babolat VS of Lyon, France. The Head®branded racquets were produced by HEAD Sport GmbH of Kennelbach,Austria.

The three prototype racquets built in accordance with implementations ofthe present invention are referred to as the Flex Prototype 1, the FlexPrototype 3 and the Flex Prototype 2. The three prototypes includeframes of fiber composite material including several 45 degree layers.The three Flex Prototype racquets are all 27 inches in length. The headsize or string bed area 38 of each of the Flex Prototype 1 and FlexPrototype 3 racquets was 102 sq. inches, and the head size of the FlexPrototype 2 racquet was 98 sq. inches.

All three prototype racquets exhibited exceptionally high lateralbending in the racquet lateral bending test compared to existing, priorart racquets. All three prototype racquets demonstrated a lateraldeflection of at least 6.0 mm, at least 6.5 mm, and at least 7.0 mm. Thelowest lateral deflection reading of the three prototype flex racquets(the Flex Prototype 3) was over 22 percent greater than the highestlateral deflection value of the 19 existing, prior art racquet models.The other two prototype flex prototype racquets, Flex Prototype 2 andFlex Prototype 1, exhibited lateral deflections of 7.7 mm and 10.5 mm,respectively, which are more than 35 percent and 84 percent greater thanthe highest lateral deflection value of the 19 existing, prior artracquet models, respectively. Additionally, the average lateraldeflection measurement of the three flex prototype racquets (8.4 mm) wasmore than twice the average lateral deflection measurement of the 19prior art racquets (4.1 mm) from the racquet lateral bending test.

All three prototype racquets also exhibited exceptionally highforward/rearward deflection readings, or bending, in the racquetforward/rearward bending test compared to existing, prior art racquets.All three prototype racquets demonstrated a forward/rearward deflectionof at least 8.0 mm, at least 8.5 mm, at least 9.0 mm, at least 9.5 mm,at least 10.0 mm, at least 10.5 mm and at least 11.0 mm. The lowestforward/rearward deflection reading of the three prototype flex racquets(the Flex Prototype 3) was over 45 percent greater than the highestforward/rearward deflection value of the 19 existing, prior art racquetmodels. The other two prototype flex prototype racquets, Flex Prototype2 and Flex Prototype 1, each exhibited forward/rearward deflections of12.1 mm, which is more than 57 percent greater than the highestforward/rearward deflection value of the 19 existing, prior art racquetmodels, respectively. Additionally, the average forward/rearwarddeflection measurement of the three flex prototype racquets (11.8 mm)was more than twice the average forward/rearward deflection measurementof the 19 prior art racquets (5.7 mm) from the racquet forward/rearwardbending test.

The results of testing the three prototype flex racquets and 19 existingprior art racquet under the racquet torsional stability testdemonstrates that despite the exceptionally and uniquely high lateralbending flexibility and high forward/rearward bending flexibility, theprototype racquets maintain a high level of torsional stability. Underimplementations of the present invention, racquets can provideunprecedented levels of lateral flexibility and forward/rearwardflexibility while maintaining a desirable level of torsional stability.Therefore, racquets built in accordance with the present inventionprovide exceptional feel, with increased levels of control, particularlyfor players who impart spin onto the ball during play, while maintaininga high level of torsional stability. With a high level of torsionalstability, racquets built in accordance with the present invention,provide exceptional control even on off-center hits.

The three flex prototype racquets exhibited torsional deflectionmeasurements under the racquet torsional stability test of 3.9 degreesfor the Flex Prototype 3, and 4.9 degrees for the Flex Prototype 2 andthe Flex Prototype 1 prototype racquets. The deflection measurementsfrom the racquet torsional stability test for the three flex prototyperacquets are less than 5.5 degrees and less than 5.0 degrees. Theaverage torsional stability measurement under the racquet torsionalstability test for the 19 existing prior art racquets is 4.4 degrees,which is within 0.5 degrees above and below the three prototype flexracquets.

Racquets built in accordance with the present invention can exhibitadvantageously low vibration characteristics providing lower shock andvibrational energy and an improved feel for the user. A modal analysiswas performed on the three prototype racquets built in accordance withimplementations of the present invention (the Flex Prototype 1, the FlexPrototype 3 and the Flex Prototype 2) and the 19 existing prior artracquets. Referring to FIG. 18, the modal analysis utilizes a modelanalysis system 180 including a computer or processor 182, a memory 184,a signal analyzer 186, a hammer 188, an accelerometer 189 and a modalanalysis frame 190. The modal analysis system 180 includes modalanalysis software code, such as STAR Modal Software provided by SpectralDynamics, Inc. of San Jose, Calif. The signal analyzer 186 can be aCougar Dynamic Signal Analyzer also provided by Spectral Dynamics, Inc.The modal analysis frame 190 allows for the racquet 10 to be suspendedin a free-free condition such as through the use of rubber bands 191. Inother implementations, the modal analysis frame can be other structuresor supports that allow for a free-free suspension of the racquet formodal analysis. The accelerometer 189 is removably attached to the frame12 of the racquet 10. Each racquet 10 was suspended in a free-freecondition in the modal analysis frame 190 and acceleration measurementsfrom the accelerometer 189 were taken using the hammer 188, which isimpacted against the racquet 10 at the multiple testing positions aboutthe racquet 10. The accelerometer 189 senses the vibration from thehammer impacts and sends a signal to the signal analyzer 186. The signalanalyzer 186 is operably connected to the processor 182 and the memory184. The modal analysis provides a vibration frequency value for theracquet 10.

The modal analysis vibration results as shown in Table 2 belowdemonstrate that the racquets built in accordance with implementationsof the present invention provide significantly lower frequency valuesthan the 19 existing prior art racquets. Racquets produced in accordancewith implementations of the present invention exhibit frequency valuesthat are lower than 140 Hz. In other implementations of the presentinvention, racquets 10 exhibit a frequency value that is less than 135Hz. In other implementations of the present invention, racquets 10exhibit a frequency value that is less than 130 Hz. In otherimplementations of the present invention, racquets 10 exhibit afrequency value that is less than 125 Hz. In other implementations ofthe present invention, racquets 10 exhibit a frequency value that isless than 120 Hz. In other implementations of the present invention,racquets 10 exhibit a frequency value that is less than 115 Hz. In otherimplementations of the present invention, racquets 10 exhibit afrequency value that is less than 110 Hz. The modal analysis of thethree flex prototype racquets demonstrated racquet frequency values of114 Hz, 115 Hz and 127 Hz, all of which are significantly lower than the19 existing prior art racquets also measured under modal analysis. Thefrequency values of the 19 existing, prior art racquets range from 140Hz to 191 Hz, which are 10 to 36 percent higher than the highestfrequency value of the three flex prototype values (the Flex Prototype2). The frequency values of the 19 existing, prior art racquets are atleast 21 to 66 percent higher than frequency values of the remaining twoflex prototype racquets. The significantly lower frequency values of theracquets built in accordance with implementations of the presentinvention can result in racquets that provide improved feel for user,and help to reduce player fatigue over time.

TABLE 2 RACQUET FREQUENCY RESULTS FROM MODAL ANALYSIS FREQUENCY RACQUETMODEL (Hz) Flex Prototype 2 115.0 Flex Prototype 3 127.0 Flex Prototype1 114.0 Wilson Ultra 2 MP 183.0 Wilson PS 5.5 SI 153.0 Wilson ProfileComp 177.0 Head Radical Tour 155.0 Prince Graphite MP 159.0 Prince Tour100 142.0 Wilson Sting 140.0 Wilson Ultra 2 171.0 Wilson Ultra 85 155.0Wilson Aggressor 140.0 Wilson Galaxy 156.0 Wilson Profile 199.0 WilsonHammer 6.2 191.0 Babolat Aero 165.0 Babolat Pure Drive 177.0 HeadRadical mp 166.0 Wilson Ultra 100 172 Wilson Blade 98 164

The incorporation of the present invention significantly improves theracquet's performance by increasing the lateral and forward/rearwardflexibility of the racquet while maintaining a high level of torsionalstability. Racquets built in accordance with the present inventionprovide a racquet with better feel and increased dwell time for theplayer, particularly for players who seek to impart a topspin onto aball during play. Racquets built in accordance with the presentinvention address the lateral load that is applied to the racquet duringthe performance of a topspin swing and flex to improve the playabilityand performance of the racquet during such topspin swings. The presentinvention provides a racquet with increased lateral flexibility,increased forward/rearward flexibility and reduced levels of racquetvibration while maintaining high levels of torsional stability. Racquetsbuilt in accordance with the present invention improve the playabilityand performance of the racquet without requiring a significantly largerhead size negatively affecting the moment of inertia of the racquet. Theresult is a significantly improved racquet that is particularly suitedfor highly skilled players.

While the preferred implementations of the present invention have beendescribed and illustrated, numerous departures therefrom can becontemplated by persons skilled in the art. Therefore, the presentinvention is not limited to the foregoing description but only by thescope and spirit of the appended claims.

1. A tennis racquet comprising: a frame extending along a longitudinalaxis and including a head portion, a handle portion, and a throatportion positioned between the head portion and the handle portion, thehead portion forming a hoop that defines a string bed plane, the throatportion including a pair of throat elements, at least the head portionand the throat portion of the racquet being formed at least in part of afiber composite material, the fiber composite material including aplurality of ply arrangements, each of the ply arrangements including apair of plies with one ply having a first plurality of fibers defining afirst angle with respect to a composite axis and the other ply having asecond plurality of fibers defining a second angle with respect to thecomposite axis, the pair of plies including at least one resin formed ofa thermoset material, the first and second angles being substantiallythe same except the first and second angles have opposite angularpolarities with respect to the composite axis, the head portionincluding at least three ply arrangements overlaying each other, and thefirst and second angles of at least two of the at least three plyarrangements are at least 35 degrees.
 2. The tennis racquet of claim 1,wherein the first and second angles of at least two of the at leastthree ply arrangements are at least 40 degrees.
 3. The tennis racquet ofclaim 1, wherein the at least three ply arrangements is at least fourply arrangements, and wherein the first and second angles of at leastthree of the at least four ply arrangements are at least 35 degrees. 4.The tennis racquet of claim 1, wherein the at least three plyarrangements is at least four ply arrangements, and wherein the firstand second angles of at least three of the at least four plyarrangements are at least 40 degrees.
 5. The tennis racquet of claim 1,wherein the at least three ply arrangements is at least four plyarrangements, and wherein the first and second angles of at least fourof the at least four ply arrangements are at least 35 degrees.
 6. Thetennis racquet of claim 1, wherein the at least three ply arrangementsis at least four ply arrangements, and wherein the first and secondangles of at least four of the at least four ply arrangements are atleast 40 degrees.
 7. The tennis racquet of claim 1, wherein the at leastthree ply arrangements is at least five ply arrangements, and whereinthe first and second angles of at least three of the at least five plyarrangements are at least 35 degrees.
 8. The tennis racquet of claim 1,wherein the at least three ply arrangements is at least five plyarrangements, and wherein the first and second angles of at least threeof the at least five ply arrangements are at least 40 degrees.
 9. Thetennis racquet of claim 1, wherein the at least three ply arrangementsis at least six ply arrangements, and wherein the first and secondangles of at least three of the at least six ply arrangements are atleast 35 degrees.
 10. The tennis racquet of claim 1, wherein the atleast three ply arrangements is at least six ply arrangements, andwherein the first and second angles of at least three of the at leastsix ply arrangements are at least 40 degrees.
 11. The tennis racquet ofclaim 1, wherein the at least three ply arrangements is at least six plyarrangements, and wherein the first and second angles of at least fourof the at least six ply arrangements are at least 40 degrees.
 12. Thetennis racquet of claim 1, wherein a majority of the fiber arrangementsinclude carbon fibers.
 13. The tennis racquet of claim 1, wherein atleast 75 percent of the fiber arrangements include carbon fibers. 14.The tennis racquet of claim 1, wherein each of the plies include aresin, and wherein each of the plies has a fiber area weight of at least50 g/m².
 15. The tennis racquet of claim 1, wherein at least a portionof each of the head portion, the throat portion and the handle portionare formed of a fiber composite material.
 16. The tennis racquet ofclaim 1, wherein the racquet is capable of being tested under a racquetlateral bending test, wherein the lateral bending test includes mountingthe racquet in a first orientation to a first test fixture at a firstlongitudinal location, attaching a clamp to the racquet at a secondlocation, operably engaging a deflection indicator to the clamp,applying a first predetermined weight to the racquet at a thirdlocation, and removing the first weight to obtain a lateral deflectionmeasurement of the racquet with respect to the longitudinal axis, andwherein, when the racquet is tested under the racquet lateral bendingtest, the racquet has a lateral deflection of at least 6.0 mm whenmeasured in a direction that is parallel to the string bed plane andperpendicular to the longitudinal axis.
 17. The tennis racquet of claim1, wherein the racquet is capable of being tested under a racquetforward/rearward bending test, wherein the forward/rearward bending testincludes mounting the racquet in a second orientation to a first testfixture at a first longitudinal location, operably engaging a deflectionindicator to the racquet at a fourth location, applying a secondpredetermined weight to the racquet at a fifth location, and removingthe second predetermined weight to obtain a forward/rearward deflectionmeasurement with respect to the longitudinal axis, and wherein, when theracquet is tested under the racquet forward/rearward bending test, theracquet has a forward/rearward deflection with respect to thelongitudinal axis of at least 9.0 mm when measured in a direction thatis perpendicular to the string bed plane and perpendicular to thelongitudinal axis.
 18. The tennis racquet of claim 1, wherein theracquet is capable of being tested under a racquet torsional stabilitytest, wherein the torsional stability test includes mounting the racquetto second and third test fixtures at sixth and seventh locations of theracquet, respectively, placing a third predetermined weight on an armextending from the second test fixture to place a torsional load on tothe racquet, removing the third predetermined weight to obtain anangular deflection about the longitudinal axis, and wherein, when theracquet is tested under the racquet torsional stability test, theracquet has an angular deflection of less than 5.5 degrees about thelongitudinal axis.
 19. The tennis racquet of claim 16, wherein theracquet is capable of being tested under a forward/rearward bendingtest, wherein the racquet forward/rearward bending test includesmounting the racquet in a second orientation to the first test fixtureat the first longitudinal location, operably engaging a deflectionindicator to the racquet at a fourth location, applying a secondpredetermined weight to the racquet at a fifth location, and removingthe second predetermined weight to obtain a forward/rearward deflectionmeasurement with respect to the longitudinal axis, and wherein, when theracquet is tested under the racquet forward/rearward bending test, theracquet has a forward/rearward deflection with respect to thelongitudinal axis of at least 9.0 mm when measured in a direction thatis perpendicular to the string bed plane and perpendicular to thelongitudinal axis.
 20. The tennis racquet of claim 16, wherein theracquet is capable of being tested under a racquet torsional stabilitytest, wherein the racquet torsional stability test includes mounting theracquet to second and third test fixtures at sixth and seventh locationsof the racquet, respectively, placing a third predetermined weight on anarm extending from the second test fixture to place a torsional load onto the racquet, removing the third predetermined weight to obtain anangular deflection about the longitudinal axis, and wherein, when theracquet is tested under the racquet torsional stability test, theracquet has an angular deflection of less than 5.5 degrees about thelongitudinal axis.
 21. The tennis racquet of claim 19, wherein theracquet is capable of being tested under a racquet torsional stabilitytest, wherein the racquet torsional stability test includes mounting theracquet to second and third test fixtures at sixth and seventh locationsof the racquet, respectively, placing a third predetermined weight on anarm extending from the second test fixture to place a torsional load onto the racquet, removing the third predetermined weight to obtain anangular deflection about the longitudinal axis, and wherein, when theracquet is tested under the racquet torsional stability test, theracquet has an angular deflection of less than 5.5 degrees about thelongitudinal axis.
 22. The tennis racquet of claim 17, wherein theracquet is capable of being tested under a racquet torsional stabilitytest, wherein the racquet torsional stability test includes mounting theracquet to second and third test fixtures at sixth and seventh locationsof the racquet, respectively, placing a third predetermined weight on anarm extending from the second test fixture to place a torsional load onto the racquet, removing the third predetermined weight to obtain anangular deflection about the longitudinal axis, and wherein, when theracquet is tested under the racquet torsional stability test, theracquet has an angular deflection of less than 5.5 degrees about thelongitudinal axis.
 23. The tennis racquet of claim 1, wherein each plyof the pair of plies are a sheet of unidirectional fibers within andpermeated throughout the resin in a non-braided and non-woven manner.